Selective adsorption and determination of hexavalent chromium ions using graphene oxide modified with amino silanes

Abstract

Novel adsorbents are described for the preconcentration of chromium(VI). Graphene oxide (GO) was modified with various amino silanes containing one, two, or three nitrogen atoms in the molecule. These include 3-aminopropyltriethoxysilane (APTES), N-(3-trimethoxysilylpropyl)ethylenediamine (TMSPEDA), and N1-(3-trimethoxysilylpropyl)diethylenetriamine (TMSPDETA). The resulting GO derivatives were characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and energy-dispersive X-ray fluorescence spectrometry (EDXRF). Adsorption studies show that these GO based sorbents are highly selective for Cr(VI) in the presence of Cr(III) at pH 3.5. Although the amino silanes applied in modification of GO contain different numbers of nitrogen atoms, the maximum adsorption capacities of GO derivatives are very similar (13.3–15.1 mg·g−1). Such results are in accordance with spectroscopy studies which show that the amount of amino silanes attached to GO decreases in the order of APTES > TMSPEDA > TMSPDETA. The APTES-modified GO was applied to selective and sensitive extraction of Cr(VI) ions prior to quantitation by low-power EDXRF using the Cr Kα line. The Cr(VI) ions need not be eluted from the solid adsorbent. The method has a 0.17 ng·mL−1 detection limit, and the recovery is 99.7 ± 2.2% at a spiking level of 10 ng·mL−1. The method was successfully applied to the determination of Cr(VI) in water samples. Graphical abstractGraphene oxide adsorbents modified with various amino silanes are described for the preconcentration and speciation of trace and ultratrace levels of chromium ions. Electronic supplementary materialThe online version of this article (10.1007/s00604-017-2640-2) contains supplementary material, which is available to authorized users.

The development of a ternary nanocomposite for the removal of Cr(vi) ions from aqueous solutions

“…A dose of 1 g L À1 of each adsorbent was used to treat 25 mL solution of 60 mg L À1 Cr(VI) at pH 2 for 60 min at 30 C. Pure GO QDs exhibit small values of R% and q of 77.7% and 46.64 mg g À1 , respectively, for the adsorption of Cr(VI) through electrostatic interactions coupled with Cr(VI) reduction to Cr(III) and followed by Cr(III) complexation. 48,54 At a low pH value of 2, the removal of Cr(VI) in the aqueous phase is faster since the negatively charged Cr(VI) species migrate to the positive surface of the GO QDs (protonated hydroxyl groups and carbonyl groups) with the help of electrostatic driving forces. Cr(VI) reduction to Cr(III) by contact with the electron-donor groups of GO QDs (OH À groups) occurs during the adsorption process and the reduced Cr(III) remains in the aqueous solution.…”

Performance Differences of Hexavalent Chromium Adsorbents Caused by Graphene Oxide Drying Process

“…Recently, we showed that the adsorbents synthesized by chemically bonding GO and amino-silanes have excellent performance in chromium adsorption (260.74 mg g −1 ) 25 . However, in the similar work by Janik et al (2018), adsorbents have relatively low Cr(VI) adsorption capacities (13.3-15.1 mg g −1 ) and the opposite order of Lee et al (2020)'s 28 . The minor yet remarkable difference between these two studies, which many researchers overlooked, is the use of different approaches for the preparation of GO.…”

Trace determination of uranium preconcentrated using graphene oxide by total reflection X‐ray fluorescence spectrometry

“…Thus, TXRF is a suitable method for determining uranium in liquid samples by using U L X‐ray lines when uranium is separated from rubidium. Recently, graphene‐based materials, which are new carbon‐based materials that are of interest in separation science, are used in solid phase extraction to measure trace metal ions . Graphene has extraordinary properties, including nanosize, high surface area, thermal and chemical stability, and excellent adsorption affinity to metal ions.…”

“…Recently, graphene-based materials, which are new carbon-based materials that are of interest in separation science, are used in solid phase extraction to measure trace metal ions. [26][27][28][29][30][31][32] Graphene has extraordinary properties, including nanosize, high surface area, thermal and chemical stability, and excellent adsorption affinity to metal ions. These properties have led to graphene-based material becoming a desirable adsorbent in a popular sample preparation technique known as solid phase extraction.…”